ssa_rewrite: Correct recursive trivial phi elimination

src/shader_recompiler/ir/basic_block.cpp

@@ -19,12 +19,14 @@ void Block::AppendNewInst(Opcode op, std::initializer_list<Value> args) {
 
 Block::iterator Block::PrependNewInst(iterator insertion_point, const Inst& base_inst) {
     Inst* const inst{inst_pool->Create(base_inst)};
+    inst->SetParent(this);
     return instructions.insert(insertion_point, *inst);
 }
 
 Block::iterator Block::PrependNewInst(iterator insertion_point, Opcode op,
                                       std::initializer_list<Value> args, u32 flags) {
     Inst* const inst{inst_pool->Create(op, flags)};
+    inst->SetParent(this);
     const auto result_it{instructions.insert(insertion_point, *inst)};
 
     if (inst->NumArgs() != args.size()) {

src/shader_recompiler/ir/ir_emitter.h

@@ -330,7 +330,6 @@ private:
     template <typename T = Value, typename... Args>
     T Inst(Opcode op, Args... args) {
         auto it{block->PrependNewInst(insertion_point, op, {Value{args}...})};
-        it->SetParent(block);
         return T{Value{&*it}};
     }
 
@@ -348,7 +347,6 @@ private:
         u32 raw_flags{};
         std::memcpy(&raw_flags, &flags.proxy, sizeof(flags.proxy));
         auto it{block->PrependNewInst(insertion_point, op, {Value{args}...}, raw_flags)};
-        it->SetParent(block);
         return T{Value{&*it}};
     }
 };

src/shader_recompiler/ir/microinstruction.cpp

@@ -180,8 +180,8 @@ void Inst::ClearArgs() {
 void Inst::ReplaceUsesWith(Value replacement, bool preserve) {
     // Copy since user->SetArg will mutate this->uses
     // Could also do temp_uses = std::move(uses) but more readable
-    boost::container::list<IR::Use> temp_uses = uses;
+    const auto temp_uses = uses;
-    for (auto& [user, operand] : temp_uses) {
+    for (const auto& [user, operand] : temp_uses) {
         DEBUG_ASSERT(user->Arg(operand).Inst() == this);
         user->SetArg(operand, replacement);
     }

src/shader_recompiler/ir/passes/ssa_rewrite_pass.cpp

@@ -270,6 +270,7 @@ public:
         block->SsaSeal();
     }
 
+private:
     template <typename Type>
     IR::Value AddPhiOperands(Type variable, IR::Inst& phi, IR::Block* block) {
         for (IR::Block* const imm_pred : block->ImmPredecessors()) {
@@ -283,7 +284,7 @@ public:
         const size_t num_args{phi.NumArgs()};
         for (size_t arg_index = 0; arg_index < num_args; ++arg_index) {
             const IR::Value& op{phi.Arg(arg_index)};
-            if (op.Resolve() == same.Resolve() || op == IR::Value{&phi}) {
+            if (op.Resolve() == same.Resolve() || op.Resolve() == IR::Value{&phi}) {
                 // Unique value or self-reference
                 continue;
             }
@@ -308,10 +309,10 @@ public:
             ++reinsert_point;
         }
         // Reinsert the phi node and reroute all its uses to the "same" value
+        const auto users = phi.Uses();
         list.insert(reinsert_point, phi);
         phi.ReplaceUsesWith(same);
-        // TODO: Try to recursively remove all phi users, which might have become trivial
+        // Try to recursively remove all phi users, which might have become trivial
-        const auto users = phi.Uses();
         for (const auto& [user, arg_index] : users) {
             if (user->GetOpcode() == IR::Opcode::Phi) {
                 TryRemoveTrivialPhi(*user, user->GetParent(), undef_opcode);